Work off that extra winter layer: By adding a few key strength moves, you'll turn your walk into a circuit-training, flab-eliminating routine that also tones legs and arms. In a study from the South Shore YMCA in Quincy, MA, exercisers who alternated between strength moves and cardio for 25 minutes three times a week for 12 weeks lost a whopping 4 percent of their body fat. "Circuit training is a great two-in-one workout," says Tracey Staehle, certified fitness trainer and creator of the Walking Strong DVDs. "You're raising your heart rate and burning calories — and you build muscle, which can boost your metabolism and help you burn more calories throughout the day."